Two substructures in the nearby stellar halo found in Gaia and RAVE

Abstract

We use the second Gaia data release (Gaia DR2), combined with RAVE spectroscopic surveys, to identify the substructures in the nearby stellar halo. We select 3,845 halo stars kinematically and chemically, and determine their density distribution in energy and angular momentum space. To select the substructures from overdensities, we reshuffle the velocities and estimate their significance. Two statistically significant substructures, GR-1 and GR-2, are identified. GR-1 has a high binding energy and small $z$-angular momentum. GR-2 is metal-rich but retrograde. They are both new substructure, and may be accretion debris of dwarf galaxies.

arXiv comment8 pages, 9 figures, ApJ in press

References in corpus (43)

• The Sloan Digital Sky Survey: Technical Summary
• Gaia Data Release 2. Summary of the contents and survey properties
• scikit-image: Image processing in Python
• Gaia Data Release 2: The astrometric solution
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• The New Galaxy: Signatures of its Formation
• The mass distribution and gravitational potential of the Milky Way
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• Tracing Galaxy Formation with Stellar Halos I: Methods
• Co-formation of the Galactic disc and the stellar halo
• The Radial Velocity Experiment (RAVE): first data release
• The Field of Streams: Sagittarius and its Siblings
• Gaia Data Release 2: using Gaia parallaxes
• Two Stellar Components in the Halo of the Milky Way
• LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) The survey science plan
• The Radial Velocity Experiment (RAVE): Fifth Data Release
• Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
• Building up the Stellar Halo of the Galaxy
• A Spectroscopic Study of the Ancient Milky Way: F- and G-Type Stars in the Third Data Release of the Sloan Digital Sky Survey
• An Orphan in the "Field of Streams"
• Detection of a 60 Degree-Long Dwarf Galaxy Debris Stream
• The Milky Way Tomography with SDSS: III. Stellar Kinematics
• Gaia reveals a metal-rich in-situ component of the local stellar halo
• Spectroscopy of QUEST RR Lyrae Variables: the new Virgo Stellar Stream
• The Orbit of the Orphan Stream
• The Overdensity in Virgo, Sagittarius Debris, and the Asymmetric Spheroid
• A box full of chocolates: The rich structure of the nearby stellar halo revealed by Gaia and RAVE
• Stellar Streams and Clouds in the Galactic Halo
• Halo streams in the 7th SDSS data release
• The slight spin of the old stellar halo
• Anisotropy of the Milky Way's stellar halo using K giants from LAMOST and $Gaia$
• The Fractions of Inner- and Outer-Halo Stars in the Local Volume
• The dynamically selected stellar halo of the Galaxy with Gaia and the tilt of the velocity ellipsoid
• A new catalogue of radial velocity standard stars from the APOGEE data
• A comprehensive view of the Virgo Stellar Stream
• Galactic googly: the rotation-metallicity bias in the inner stellar halo of the Milky Way
• Brightest Cluster Galaxy Alignments in Merging Clusters
• Photometric Metallicity Calibration with SDSS and SCUSS and its Application to distant stars in the South Galactic Cap
• Galactic Stellar Populations from Photometric Metallicity Distribution Functions

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• Dynamically Tagged Groups of Metal-Poor Stars from the Best \& Brightest Survey
• Chemo-Dynamically Tagged Groups of CEMP Stars in the Halo of the Milky Way. I. Untangling the Origins of CEMP-$s$ and CEMP-no Stars
• The R-Process Alliance: Chemo-Dynamically Tagged Groups II. An Extended Sample of Halo $r$-Process-Enhanced Stars
• Dynamically Tagged Groups of Metal-Poor Stars II. The Radial Velocity Experiment Data Release 6
• The global structure of the Milky Way's stellar halo based on the orbits of local metal-poor stars